Setting the Number of Threads Using an OpenMP* Environment Variable

You can set the number of threads using the environment variable OMP_NUM_THREADS. To change the number of OpenMP threads, use the appropriate command in the command shell in which the program is going to run, for example:

  • For the bash shell, enter:
    export OMP_NUM_THREADS=<number of threads to use>
  • For the csh or tcsh shell, enter:
    setenv OMP_NUM_THREADS <number of threads to use>

For more complete information about compiler optimizations, see our Optimization Notice.
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